666251 has 4 divisors (see below), whose sum is σ = 668904. Its totient is φ = 663600.

The previous prime is 666233. The next prime is 666269. The reversal of 666251 is 152666.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 152666 = 2 ⋅76333.

It is an interprime number because it is at equal distance from previous prime (666233) and next prime (666269).

It is a cyclic number.

It is not a de Polignac number, because 666251 - 2⁶ = 666187 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 666251.

It is not an unprimeable number, because it can be changed into a prime (666751) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 905 + ... + 1466.

It is an arithmetic number, because the mean of its divisors is an integer number (167226).

2⁶⁶⁶²⁵¹ is an apocalyptic number.

666251 is a deficient number, since it is larger than the sum of its proper divisors (2653).

666251 is a wasteful number, since it uses less digits than its factorization.

666251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2652.

The product of its digits is 2160, while the sum is 26.

The square root of 666251 is about 816.2419984294. The cubic root of 666251 is about 87.3398867849.

The spelling of 666251 in words is "six hundred sixty-six thousand, two hundred fifty-one".